Allergy can be defined as a state of immune responsiveness in an animal to an exogenous antigen (or allergen) that is not otherwise harmful to the animal.
Environmental allergens include allergens that derive from organisms such as plants, molds, animals, and insects. Examples of environmental allergens include plant pollens, and mold spores. Other environmental allergens are found in the excretions of furred animals, and insects, such as mites and cockroaches.
Environmental allergens pose a health threat to people of all ages, most particularly children. The presence of such allergens in the environment can result in symptoms or responses that range from mild rhinitis, to skin problems (e.g., itching and hives), asthma, acute respiratory distress, and even to life-threatening anaphylactic reactions. Most cat allergies are caused by a small stable glycoprotein called Fel d1 (Feline domesticus allergen number 1). Cat allergens such as Fel d1 can be released from the litter box into the surrounding area. For example, cats often scratch and shift the cat litter, creating dust by which the cat allergens become airborne in the surrounding area. Similarly, scooping the cat litter can circulate cat allergens into the air.
Fel d1 can be particularly problematic because it is lightweight (35 kDa) and thus remains suspended in the air for an extended amount of time. Furthermore, Fel d1 is a sticky protein and consequently adheres to articles within the area surrounding the litter box, such as carpets, walls, furniture, clothing, and curtains, thereby making this allergen difficult to remove after it has circulated from the litter box.
To the inventors' best knowledge, at this time there is no known method for loading an environmental space and quantitatively measuring Fel d1 that is emitted into the environment from soiled cat litter.